The real issue I had with this is that you can't control the camera (or if you can, you certainly can't do it with the mouse). It would be a tonne easier to play if you can move the camera with the mouse so you can direct Sonic in the way it's facing (like GDK/Freerunner).
Also, the stage is too bland. It's clearly a corridor with half the textures missing (or if they're not missing, those white ramps look very silly). Also not keen on the random transition from grass to sand/stone.
You should work on giving the player a wide, open space to explore with different land-masses to explore. Take a look at Robo Blast 2 for influence on how to make an interesting 3D stage to explore.